For the examples in this paper, we migrated the prestack data with a shot-profile migration algorithm, imaging the cross-correlation of upgoing and downgoing wavefields at zero-time Claerbout (1971); however, the methodology is also applicable for ``survey-sinking'' shot-geophone algorithms based on the double square root equation Claerbout (1985).

Migrating converted waves with conventional wavefield extrapolation
algorithms simply involves extrapolating downgoing waves with the
*P*-wave velocity field, and upgoing waves with the *S*-wave velocity
field. The difficulty comes in the interpretation of common-image
gathers in terms of incidence angle at the reflector.

4/29/2001